New component of human hair discovered

Scientists have discovered a new component of human hair using an X-ray beam, a finding that may pave the way for new and improved hair products.
In addition to the three known hair regions, researchers have discovered a new intermediate zone between the cuticle and cortex.
"Hair traditionally has been constituted of three regions: medulla (central part of the hair), cortex (biggest volume fraction of the hair) and the cuticle (external part of the hair)," said project leader Vesna Stanic, a scientist at the Brazilian Synchrotron Light Source.
"We discovered a new intermediate zone, which is in between the cuticle and cortex," she told 'Discovery News'.

Stanic and her team made the discovery by combining an ultra powerful submicron X-ray beam with cross-sectional geometry.
The original goal was to study materials used in hair treatments, and how they affect hair. While doing this, Stanic wondered about the diffraction patterns of hair.

X-ray diffraction patterns of a given material can show the local arrangement of both molecular and atomic structures.
Diffraction patterns of human hair have been documented before, but they usually involved pointing the X-ray beam perpendicular to the hair fibre axis.
"We performed a full diffraction map from a 30-micron-thick cross section of hair, with an incident beam parallel to the hair axis, and then compared it to the diffraction map with the beam perpendicular to the hair axis," Stanic said.

Human hair was thought to be composed only of a fibrous protein called alpha keratin, as well as certain minerals and lipids.
The scientists were surprised to find that a key diffraction feature of alpha keratin was absent in the area between a hair strand's cuticle and cortex. The pattern instead corresponded to beta keratin.
Previously, beta-keratin was associated with reptiles and birds.
Alpha and beta keratin are similar molecules, but they have very different sizes and shapes.
"The basic difference between alpha and beta keratin is the molecule conformations. We can say that beta keratin is essentially stretched alpha keratin. Alpha keratin has a helical structure, while beta is typically arranged in sheets," Stanic said.

The research was presented at the annual meeting of the American Crystallographic Association, held in Philadelphia.